1. Field of the Invention
This invention relates to a side molding which comprises a molding proper formed of a synthetic resin compound incorporatimg therein a plasticizer and an adhesive tape integrally joined as fitting means to the molding proper.
2. Description of the Prior Art
The conventional side molding of the type described above has a double-faced adhesive tape having adhesive layers 2 formed on the opposite sides of a substratal film 1 (hereinafter referred to as "double-faced tape") and a molding proper 4 made of synthetic resin (such as, for example, polyvinyl chloride), with the double-faced tape integrally joined through the medium of either of the two adhesive layers 2 to the molding proper 4. The adhesive layer 2 on the opposite side of the molding proper is protected with a peel proper 5. The aforementioned substratal film 1 is generally formed from a flexible foamed material (such as, for example, polyethylene, chloroprene rubber, or acrylic rubber) with a view to absorbing undulations on the rear surface of the molding proper and absorbing vibrations generated in motion. The adhesive agent forming the adhesive layers 2 is required to possess a viscoelastic property at room temperature and exhibit a high adhesive property to both the object of attachment (vehicle) and the substratal film. Generally, an acrylic adhesive agent or a rubbery adhesive agent is selected. In the attached drawing, 7 denotes a metallic insert intended to confer rigidity upon the molding proper 4 and curb thermal expansion of the molding proper. Examples of the plasticizer usable in the molding proper include acid esters such as phthalic esters, aromatic carboxylates, and aliphatic dibasic esters.
The side molding of this nature has had the possibility of inducing separation between the rear side of the molding proper and the adhesive tape after a protracted standing especially after application to the vehicle. The cause for this trouble has not yet been elucidated. It may be explained by a postulate that this separation is caused by the exudation (bleeding) of the plasticizer from within the molding proper. To be specific, when the plasticizer so exuding lacks compatibillity with the adhesive agent, it forms a layer in the boundary between the rear side of the molding proper and the adhesive layer and consequently causes breakage of the boundary. When the exuding plasticizer possesses compatibility with the adhesive agent, it diffuses itself the into adhesive agent to lower the viscosity of the adhesive agent and bring about destruction of cohesion. This trend, when coupled with the deterioration of the adhesive agent, becomes all the more conspicuous when the molding is set in position on the vehicle and exposed directly to the outdoor conditions such as the effects of heat and light.